Field of the Invention
The present invention relates to wireless communications and, more particularly, to a reporting method for the mobility information of a user equipment and an apparatus for supporting the same.
Related Art
The 3rd Generation Partnership Project (3GPP) long term evolution (LTE) which is an improvement of Universal Mobile Telecommunications System (UMTS) is introduced as 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in downlink and uses Single Carrier-frequency division multiple access (SC-FDMA) in uplink. And multiple input multiple output (MIMO) having maximum 4 antennas is adopted. Recently, the 3GPP LTE-Advanced (LTE-A) which is an evolution of the 3GPP LTE has been discussed.
In a specific location within the coverage of the macro cell having wide coverage, a cell having narrow coverage such as a micro cell, a femto cell, a pico cell, and the like may be installed. Such cells can be called small cells.
Since a user equipment which is a representative of mobile devices moves, the quality of service which is currently provided for the user equipment may be degraded or the user equipment may find a cell that can provide better service. According to this, the user equipment may move to a new cell, which is called the mobility performance of the user equipment.
Each cell has fixed service coverage, however the user equipment moves on wireless communication systems with variable speed, therefore, the frequency of inter-cell movement of the user equipment may depend on circumstances. In order to support adequate inter-cell movement of the user equipment considering actual moving state of the user equipment, the mobility state estimation (MSE) and the method of scaling mobility parameter have been supported.
The mobility information related to the mobility state of the user equipment may be very important source for the determination of configuration optimized for the user equipment by network or for the optimization of network operation. However, since the network may not know if the user equipment has valid mobility information to report, the network may not properly request the corresponding information. In addition, unlike the mobility information that has been already reported, in case that the mobility information is updated on the user equipment, the network performs operation based on the existing mobility information since the network does not know whether the mobility information is updated. Accordingly, a method that the user equipment reports valid mobility information to the network is required.